I'm using this case:

http://www.caselogic.com/koskin_ston...?modelid=44299

It has a plastic PDA holder riveted inside, but I ripped the plastic and rivets out. Holds the 770 perfectly w/ cover on. It's great for when I am afraid I might drop it.

Case logic sells another case, http://www.caselogic.com/koskin_pda_...?modelid=57047, that holds the contents in with an elastic strap. The 770 sorta fits this one, but an edge is left exposed.. so if you were to drop it on pavement, there is a good chance of ending up with some damage. I opted against it, and decided to modify the other one and I'm happy.

Also, the case that came with my Stowaway keyboard fits the 770 nicely, but I don't have any extras of those... heh.